Subj : Re: How to pass class-member function to pthread_create(....)?
To   : comp.programming.threads
From : Jedrzej Dudkiewicz
Date : Tue Jul 19 2005 09:51 am

> >     The C++ standard provides the guarantee that extern "C" gives C
linkage.
> > The pthreads standard gives the guarantee that pthread_create takes
> > functions with C linkage.
>
> I am sorry, but I would like to see what POSIX says about C linkage in
> pthread_create, not your comments on that. Can you make a quote?

This http://www.opengroup.org/onlinepubs/007908799/xsh/pthread.h.html says:

 The following are declared as functions and may also be declared as macros.
Function prototypes must be provided for use with an ISO C compiler.

So, it's for use with C compiler and this is the way it is used: C header is
included and linking with C library is performed.

C++ Standard says:

7.5.1 All function types, function names, and variable names have a language
linkage. The default language linkage of all function types, function names,
and variable names is C++ language linkage. Two function types with
different language linkages are distinct types even if they are otherwise
identical. (The last sentece was quoted here by Maciej Sobczak)

7.5.2 Linkage between C++ and non-C++ code fragments can be achieved using a
linkage-specification:

    linkage-specification:
        extern string-literal { delcaration-seq(here goes subscript "opt",
but...) }
        extern string-literal declaration

The string-literal indicates the required language linkage. [...]

7.5.3 Every implementation shall provide for linkage to functions written in
the C programming language, "C", and linkage to C++ functions, "C++".

We use C headers and C libraries in C++ code. The only way to achieve it in
C++ is to declare function passed to this libraries as extern "C".

JD

.